1. Field of the Invention
The present invention relates to stock unit for storing carriers, and more particularly to a stock unit, which can efficiently carry in and out carriers.
2. Description of the Related Art
In conventional, there is used a stock unit for storing carriers, on which objects is disposed, described in Published Unexamined Japanese Patent Application No. 30120.
This type of stock unit comprises a multi-stepped carrier mounting plate on which a carrier is mounted and a carrier holding member, which can go up and down in a vertical direction and move in a horizontal direction. In a case where the carrier is mounted on the carrier mounting plate by use of this type of stock unit, the carrier holding member holds the carrier, and the carrier holding member is lifted up and down in the vertical direction, and moved in the horizontal direction. Thereby, the carrier is transferred to a predetermined carrier mounting plate. The plurality of carriers, which is mounted on the carrier mounting plate, is transported to wafer transfer means by a transport mechanism, and the carriers are transferred to a wafer boat for heat treatment by wafer transfer means.
However, in the conventional stock unit, it is impossible to transport the carriers to be supplied from an exterior at a carrier port while the wafer is transferring to the wafer boat in the transfer between the wafer boat and the carrier. Due to this, time waiting is generated in a part of the function of the carrier transport. For this reason, the carriers stay before the carrier port and throughput deteriorates. Moreover, there is a problem in that flow of carrier transport is stopped in a series of a semiconductor manufacture.